Our modern life depends on rare earth elements, and sometimes we don’t have enough to keep up with the growing demand.
Because of their special properties, these 17 metallic elements are crucial ingredients in computer screens, cell phones and other electronics, compact fluorescent lamps, medical imaging devices, lasers, fiber optics, pigments, polishing powders, industrial catalysts — the list goes on and on (SN Online: 1/16/23). Rare earth compounds are an essential part of the powerful magnets and rechargeable batteries in electric vehicles and renewable energy technologies needed to achieve a low-carbon or zero-carbon future.
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In 2021, the world will mine 120,000 tons of rare earths — nearly 32 times as much as was mined in the mid-1950s. And demand is only increasing. By 2040, experts estimate, we will need up to seven times as much rare earth as today.
Satisfying that appetite will not be easy. Rare earth elements are not found in accumulated deposits. Miners excavate huge amounts of ore, use physical and chemical processes to extract rare earths, and then separate them. Energy conversion is intensive and dirty, requiring toxic chemicals and often generating small amounts of radioactive waste that can be safely disposed of. Another concern is access: China has a near monopoly on mining and processing; The United States has only one active mine (SN Online: 1/1/23).
For most of the earth’s rarer jobs, they are not good substitutes. In order to help meet future demand and diversify the supply chain – and perhaps even more rare earth recovery “greener” – researchers are looking for alternatives to conventional mining.
Proposals include everything from extracting metals from waste coal to real-life, out there ideas like mining the moon. But the most likely approximation is for immediate recycling. “Recycling plays a very important and central role,” says Ikenna Nlebedim, a materials scientist at Ames National Laboratory in Iowa and the Department of Energy’s Critical Materials. “This is not to say that we are out of our recycling of critical materials.”
However, in our market for rare earth magnets, for example, for about 10 years from now, recycling could satisfy as much as a quarter of the demand for rare earths, according to some estimates. “It’s huge,” he said.
But before the rare earths in an old laptop can be recycled as regularly as the aluminum in vacuum soda, there are technological, economic and logistical hurdles to overcome.
Why is the earth so rare to elicit a challenge?
Recycling obviously seems like a way to get rarer earths. It is standard practice in the United States and Europe to recycle from 15 to 70 percent of other metals, such as iron, copper, aluminum, nickel and tin. Today, however, only about 1 percent of rare earth elements are recycled in ancient crops, says Simon Jowitt, an economic geologist at the University of Nevada, Las Vegas.
“Copper wiring can be recycled into more copper wiring. Iron can only be thrown into more iron,” he said. But many rare earth products are “not very recyclable in themselves.”
Rare earths are often mixed with other metals in contact with crusts and similar products, making removal difficult. In a way, recycling rare earths from discarded objects mimics the challenge of extracting them from the mouth and separating them from each other. Traditional rare earth recycling methods also require hazardous chemicals such as hydrochloric acid and a lot of heat, and thus a lot of energy. On the environmental footprint, cost recovery may not be worthwhile given the small yield of rare earths. For example, a hard drive, a few P.*; offer some products like mg.
Chemists and materials scientists, however, are trying to develop smarter recycling. Their techniques try to bypass the microbes to work, the acids of traditional methods of digging, or extraction and separation.
Microbial partners can help recycle rare earths
Access is based on minimal partners. Gluconobacter Bacteria naturally produce organic acids that can extract rare earths, such as lanthanum and cerium, from spent catalysts used in petroleum refining or fluorescent phosphors used in lighting. Bacterial acids are less environmentally harmful than hydrochloric acid or other traditional metal-causing acids, says Yoshiko Fujita, a biogeochemist at the Idaho National Laboratory in Idaho Falls. Fujita leads research on reuse and recycling at the Critical Institute. “It can also be degraded naturally,” he said.
In experiments, bacterial acids can recover only about a quarter of the rare earths from the catalysts and phosphorus consumed. Hydrochloric acid is much better — in some cases extracting as much as 99 per cent. But bio-based leaching is still beneficial, Fujita and colleagues in 2019 in . were reported ACS Sustainable Chemistry & Engineering.
In a hypothetical plant recycling 19,000 metric tons of catalyst used per year, the team estimated annual revenue of approximately $1.75 million. Feeding the bacteria that make the acid in-situ is expensive. In a scenario in which the bacteria are fed sugar, the total cost to produce rare earths is about $1.6 million a year, leaving only about $150,000 in profit. The switch from sugar to stalks, pods and other crop residues would, however, increase the profit by about $500,000, raising the profit to about $650,000.
Other microbes also help extract rare earths and take them even further. A few years ago, researchers discovered that some bacteria that metabolize rare earths produce a protein that mainly grabs these metals. This protein, lanmodulin, can separate rare earths from each other, such as neodymium from dysprosium – the two rare earth magnets. A lanmodulin-based system eliminates the need for many of the chemical reagents typically used in such a separation. And the waste left behind is protein – it would be biodegradable. But whether the pandat system works on a commercial scale is unknown.
How to draw rare earths away from magnets
Another approach already in commercial use uses acids and copper salts to repel rare earths from magnets, a high-value target. Neodymium iron-boron magnets are about 30 percent rare earth by weight and one of the most widely used metals in the world. One projection suggests that neodymium in active hard magnets recovered from the US alone could meet about 5 percent of world demand outside of China before the end of the decade.
Nlebedim led a team that developed a technique that uses copper salts to clean rare earths from electronic aluminum waste that contains magnets. Dunking e-waste in a copper salt solution at room temperature dissolves the rare earths in the magnets. Another can be drawn from its own recycling, and the copper solution can be returned to a larger salt solution. Then, the rare earths are solidified and, with the help of added chemicals, are transformed into coal minerals called rare earth oxides. The process, which even involves waste material from magnet manufacturing that is typically wasted, can recover 90 to 98 percent of rare earths, and the material is pure enough to make new magnets, Nlebedim’s team demonstrated.
In a best-case scenario, using this method to recycle 100 tons of leftover magnet material to produce 32 tons of rare earth oxide and net more than $1 million in profit, the economic analysis of the method suggests.
This study also assessed the environmental impact of the approach. Compared to producing one kilogram of rare earth oxides through one of the main types of mining and processing used in China, the air salt method has less than half the carbon footprint. It produces an average of about 50 kilograms of carbon dioxide equivalent per kilogram of rare earth oxide versus 110, the Nlebedim team announced in 2021 ACS Sustainable Chemistry & Engineering.
But not all forms of mining are necessarily greener. One sticking point is that the process requires the burning of toxic ammonium hydroxide, which consumes a lot of energy and yet emits some carbon dioxide. Nlebedim group now veil art. “We want to decarbonize the process and make it safer,” he said.
Meanwhile, the technology seems promising enough that TdVib, an Iowa company that designs and manufactures magnetic materials and products, has licensed and built a pilot plant. The initial intention is to produce two tons of rare earth oxide per month, says Daniel Bina, TdVib president and CEO. A recycling plant drives rare earths from old hard disk data centers.
Noveones Magnetics, a company in San Marcos, Texas, now makes recycled iron-boron neodymium magnets. In typical magnet manufacturing, rare earths are prepared, transformed into metallic alloys, ground into a fine powder, magnetized, and formed into a magnet. Noveon is hitting those first two steps, says company CEO Scott Dunn.
After demagnetizing and cleaning the discarded magnets, Noveon immediately crushes them into dust before building them into new magnets. Unlike with other recycling methods, there is no need to extract and separate the rare earths first. The final product can be made up of more than 99 percent recycled magnet, Dunn says, with a small addition of rare earth virgin elements — “the secret sauce,” as he puts it — that allows the company to attribute well-to-dog magnets.
Compared to traditional magnet mining and manufacturing, Noveon’s method cuts energy use by about 90 percent, Miha Zakotnik, Noveon’s chief technology officer, and other researchers reported in 2016 Environmental Technology & Innovation. Another 2016 analysis estimated that for every kilogram of magnet produced by the Noveon method, around 12 kilograms of carbon dioxide equivalent are emitted. This is about half as much greenhouse gas as conventional magnets.
Dunn declined to share what volume of magnets Noveon is producing today or how much its magnets cost. Magnets are used in some industrial applications, such as pumps, fans and compressors, as well as some consumer power tools and other electronics.
Rare earth recycling logistical hurdles
Even as researchers understand the technological barriers, there are still logistical barriers to recycling. “We don’t have the means to collect the fruits of life that have rare earths in them,” Fujita says, “and there’s the cost of depressing the fruits.” For much of the e-discrete, before the rare earth can begin to be recycled, it must be obtained from the bits that contain those precious metals.
Noveon has a semiautomatic process for removing magnets from hard drives and other electronics.
Apple is also trying to automate the recycling process. Aster company’s robot can tear iPhones. And in 2022, Lake announced that a pair of robots named Taz and Dave would facilitate the recycling of rare earths. The Taz can pick up magnetically contained modules that are typically lost through electronic chipping. Dave can recover magnets from haptic devices, Apple’s technology that allows users to compare tactile feedback with, say, tapping on an iPhone screen.
Even with robotic assistance, however, it would be much easier if companies designed products in a way that was easily recyclable, Fujita says.
As good as recycling gets, Jowitt doesn’t see the need to ramp up mining to feed our rare earth-hungry society. But recycling is necessary. “We are dealing with inherently limited resources,” he said. “We’re trying to extract what we can rather than just dumping it in the landfill.”
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